Means for indicating the presence of radio frequency fields



IN VEN TOR GEORGE E COL MAN G. E. COLMAN MEANS FOR INDICATING THE PRESENCE OF RADIO FREQUENCY FIELDS Filed Sept. 18, 1943 March 5, 1946.

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UNITED STATES IATENT OFFICE ME FOR INDICA'I'ING m OF D10 FREQUENCY FIELDS Gels-gel. led NHL, to c. W 2. in end-r... .gzedcalamedbibemnryd Application lcptmbegli, 188. CH No. 2.000

4 Claims. (cl. sis-m) (Granted under die at a larch a, use, as wesrnso.im:mo.o.ml

Theinventiondescribedherelnmaybemanutbeli'fll'maedwcrcomingthenecessit lorobiactured and used by or tor the Government tor taining a hish i'iuerinz voltase from he R-I". governmental purposes, without the myment to fi l thereby rendering the tub punitive to m me oi any royalty thereon. cly llisht increments in the ionization I! present invention relates to me ns for i a In the specification I describe dicating the presence or radio frequency fields and in the annexed drawing show one form which and. while not limited thereto, it is particularly the indicators of the present invention may take, well suited to indicating the condition or resoit s. ever. to be clearly understood that 1 nance in radio transmittins and receiving equipdo n t wish to be limited to the construction and meat. 10 circuit herein shown and described for purpose In my copendins bnlicati n entitled. M t d mmntiw inasmuch as chances therein and means tor measuring radio trequency neld may be made within the true spirit oi the scope intensity," Serial Number 495,730, died July 22, or the invention as ni-eased in the claims here.

1943.1 disclose a method and means, for purposes to appended.

similar to the present invention, which enable ii In said drawinmtheaingle munhggch n the elimination oi a thermocouple as a component diasram oi a radio-frequen n w m; min the previously used instruments. strument made in accordance with the principles In the present invention, I aim to provide a oi! the present invention.

eensitive and accurate device, which not only Referring now mor i n w t w mm eliminates the necessity for a thermocouple. but an invention. with particular reference to the ciravoids the necessit tor an indicating meter as cuit shown in the drawing, the numeral I senwell, thus further reducins cost or manufacture erally designates a sea discharge tube, such Is and maintenance, and additionally simplifying a neon bulb. Connected in series with the tube the whole procedure of timing radio equipment, I is a resistor l and a source I or D.-C. potential.

determining modulation. etc. 8| The value 0! the D.-C. potential is such as to lnleneraLthepresentinventionconsistsoithe hartiallyionisethez'aewithinth tuhemdeause toliowins: the me to slow at a low level. The value of Aces discharge tube.suchasaneon bulb,is thensistorissuchastoheveryhighcompued oonnectedinan-Qcircuittohrinzaboutthe withthereslstanceorthepartisilyionire sas. partialionization oithesastherein. Thecomaothatchanzesinthedesreeotionization will ponents oi the circuit are such that the 11-0. have practically no effect upon the conductivity conductivity thereof remains at a substantially or the entire D.-C. circuit and the how or D. C. constant level at all times. will remain at a substantially constant level.

'I'hetieidtobeindicatedisapniiedtothetube loimtedaboutthetubelinthevicinityoi through electrostatic induction. the radio tre- 88 the electrodes thereot, is a conducting rin I, quen circuit, or which the tube constitutes a which is connected. through avariable condenser link, being completed by sroundins one at the I. to a radio-frequency pick-u device, such as electrodes of the tube ijadio-taquenm lnantenna il. tl'hewrpceeoithevariable con- .b cularlynotcdthstincontradistinctiontothetunctioningofthedeviceoi'my showmandinordertoecutlisethedesree oi copending application, in which the additional ionintiomandthereim'ethe slow,in thevicinity ionization brought sboutbythel't-lfiiield causes ct both electrodes under the influence of the anincreaeeintheiiowoi'thencanditis radio-trequeneyiieldtobeindicatedtheelectheadditiomdnQthstismadethemeasm-e trodesareshuntedwithalowc pacitanceconoithe field intensity, in the present invention. denser Ii. theadditionalicnisationhsspracticailynoeiiectlo Asanexampleoithenluqoithecomponents upontheD.-C.circuit,andthemnctioninotthe oithecircmtdeacrihedthesom-ceotn-apo device for the intended purpose is dependent tentiallmayheaboutlwvolmthestsdischarge lolclyuhontheradio-trequencyvoltasedeveloped hibelmayheaShtthndnbulhtherflistnr acrossthetuheinthecompietedR-Itcircuit. Omaybetromitoimesnhmatheflsedccnmmimparflflionhaflmotthemhtcrfldcnnrllmubeahontmmmhsndthe variableooodenserflmaybeoflikevalue atfull capacitance.

Uponmtmducingthepick-up ilintoaradioirequency field, a difierence of potential is estabiishedbetweentheconductingringlontheone handsndtheelectrodesofthetubelonthe other. thereby increasing the ionisation of the minthetubeandcausingthesametoglow at a higher level than before the application of the radio-frequency potential.

There is therefore presented a complete radiofreouency circuit from the pick-up it to ground, andinssmuchasthevalueoitheresistoriis veryhighascomparedwiththeresistanceorthe partially ionized gas of the tube, the additional ionisation of said gas, brought about by the radio-irequency potential, alters the conductivity of the D.-C. circuit to such a small extent "that it can be said that the D. C. conducted through the tube remains at a substantially constant level. 'lhe resulting ditional glow of the e throughout this specification, and in the claims. the tube I is described as being connectedinaD.-C.circuit,thisisnottobeconstrued as a limitation; rather, it is illustrative. If desired. the source I of D. C. may be replaced completes the description of the present invention. It will be noted from all of the foregoing that I have provided a very simple and inexpensive radio-frequency field indication device which is extremely sensitive. which can be made very rugged, which includes means to prevent overloading, and which enables the elimination of thermocouples and galvanometers, both of which have heretofore been incorporated in instrument; designed for purposes similar to those of the present invention.

Other advantages and applications of the present invention will readily occur to those skilled in the art to which the same relates.

I claim:

1. An indicator for oscillating fields comprising a pair of circuits, a glow-discharge tube common to both circuits, one circuit comprising a source of polarizing potential in series with said glow-discharge tube. the potential of said source being just above the striking potential of said glow-discharge tube whereby the latter is partially ionized to produce a glow of relatively low visibility, means in the other circuit responsive to said oscillating fields to vary the resistance of said glow-discharge tube, the resistance of said one circuit being high compared to the resistance of the glow-discharge tube when ionised. whereby a greater range of glow variation is available for indication of said oscillating fields.

2. A radio-frequency field-intensity indicator comprisingafirstcircuitandasecondcircuiha glow. tube having an ionizable glow-discharge pathcommontobothcircuitaasourceofpctem tialinsaldfirstcircuit and inserieswithsaid glow-discharge path, said potential being just above the striking voltage of said tube whereby said tube is caused to slow at a relatively low level of visibility. and means to expose said second circuit to electric fields to increase the ionization of said discharge path and thus increase the brightness of said glow as a function of the intensity of said fields. the resistance of said first circuit being relatively high compared to the resistance of said discharge path when fully ionized soastominimizethechangesincurrentinsaid first circuit due to ionization changes in said tube brought about by intensity changes in said electric field, whereby a greater range of glow-intensity variation is available for indication of said field-intensity changes.

8. A radio-frequency field-intensity indicator comprising at least a cathode, anode. and control electrode, a glow tube having a circuit including said anode and cathode and a source of potential in series, said potential being Just above the striking voltage of said tube. whereby said tube is caused to slow at a relatively low level of visibility, a second circuit including said control electrode and said cathode and responsive to electric fields to increase the ionization of said discharge path and thus increase the brightness of said glow as a function of the intensity of said fields, the resistance of said first circuit being relatively high compared to the average resistance of said glow tube when conducting so as to minimize the changes in current in said first circuit due to ionization changes in said tube brought about by intensity changes in said electric field, whereby a greater range of glow-intensity variation is 'available for indication of said field-intensity changes.

4. A radio-frequency field-intensity indicator comprising a first circuit and a second circuit, a glow tube having an ionizable glow-discharge path common to both circuits, a source of potential in said first circuit and in series with said glow-discharge path, said potential being just above the striking voltage of said tube. whereby said tube is caused to slow at a relatively low level of visibility, and means to expose said second circuit to electric fields to increase the ionization of said discharge path and thus increase the brightness of said glow as a function of the intensity of said fields, the resistance of said first circuit being relatively high compared to the average resistance of said discharge path when conducting so that the fiow of current produced Qatiflcate of Correction Patent N0. 2,395,850. March 5, 1946. GEORGE E. COLMAN It is hereby certified that the above numbered patent was erroneously issued to t the Government of the United States of America, as replesented by the Secretary of War whereas said patent should have been issued to the inventor, said Colman; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Offiee.

' Signed aInd sealed this 7th day of May, A. D. 1946.

LESLIE FRAZER,

First Assistant Uommiasiomr of Patents. 1 

